class Banner
	def initialize(text)
		@text = text
	end 
	
	def to_s 
		@text
	end 
	
	def +@
		@text.upcase
	end 
	
	def -@
		@text.downcase
	end 
	
	def !
		@text.reverse
	end 
end 

banner = Banner.new("Eat at David's!")
puts banner 
puts +banner 
puts -banner 
puts !banner